N6-(ferrocenmethyl)quinazolin-2,4,6-triamina (h2) and the derivatives and prodrugs thereof as antileishmanial, antiprotozoal, antiparasitic and antimicrobial agents

ABSTRACT

The use of N 6 -(ferrocenmethyl)quinazoline-2,4,6-triamine (H2), its derivatives, and prodrugs that present antimicrobial (antibiotic, microbicide), antiparasitic (parasiticide), antiprotozoal (protozoacide), and antileishmanial (leishmanicide) activities, as well as its use as a drug in vertebrates (humans and animals).

BACKGROUND

The use of N⁶-(ferrocenmethyl)quinazoline-2,4,6-triamine as an antimicrobial, antibiotic, microbicide, bacteriological, bacteriostatic, antiparasitic, antiprotozoal, or antileishmanial agent has not been previously reported.

Since the emergence of leishmaniasis in 1885, few agents have been described and used in the treatment of this disease, and these agents have variable efficiency and effectiveness. Therapeutic options are rare and include expensive drugs that are difficult to obtain, lack a coordinated registry, and may be toxic or ineffective. Antimonials, for example (including the meglumine antimoniate), were introduced in 1940 and continue to be the treatment of choice for cutaneous leishmaniasis, although the treatment regimens are longer than 20 days and can induce pancreatitis (the most frequent reason that treatment is discontinued) as well as serious electrocardiographic changes. Amphotericin B, which is nephrotoxic and hypercalcemic, is also used (Alvar J, et al., 1997. Clin. Microbiol. Rev. 10: 298-319; Alvar J, et al., 2008. Clin. Microbiol. Rev. 21: 334-359).

Other compounds used as antiparasites, such as metronidazole, present variable results, which in general reflects a lack of evidence regarding these drugs. Recently, the in vitro leishmanicidal activity of hydroxyurea was described (Martinez-Rojano H, et al., 2008. Antimicrob. Agents Chemother. 52: 3642-3647), although in vivo evidence has not been reported.

THE SUBJECT MATTER OF THE INVENTION

The present invention refers to the human or veterinary use of a compound that contains N⁶-(ferrocenmethyl)quinazoline-2,4,6-triamine, as well as its derivatives and prodrugs, as an antimicrobial (antibiotic, microbicide), antiparasitic (parasiticide), antiprotozoal (protozoacide), or antileishmanial (leishmanicide) agent.

The N⁶-(ferrocenmethyl)quinazoline-2,4,6-triamine compound, which we refer to as H2, presents antimicrobial, antiparasitic, and leishmanicide activity from 0.1 μg/ml to greater than 100 μg/ml. H2 can be used in the treatment of infections caused by microorganisms, parasites, and protozoa, including members of the Leishmania genus in particular.

DESCRIPTION OF FIGURES

FIG. 1: The biological activity of H2 toward the in vitro growth of Leishmania mexicana strain MHOM/MX/01/Tab3. A growth curve collected after 72 hours of parasite cultivation in a Neubauer chamber in the presence of the H2 is shown. The H2 concentration is shown on the horizontal axis, whereas the number of parasites/ml is shown on the vertical axis. The experiment was performed at room temperature using high-glucose Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum.

FIG. 2: Photograph obtained using an inverted microscope showing the inhibition of Leishmania growth by H2. The parasite culture shown in the left image was grown under the same conditions described in FIG. 1 but with the absence of H2. The right image shows a culture grown in the presence of 1 μg/ml of the H2 compound, indicating a clear lack of growth and destruction of the parasite in the presence of H2.

FIG. 3: A plot showing the H2 prodrug activity toward the in vitro growth of Leishmania Mexicana. To obtain a higher sensitivity in this experiment, the MNYC/BZ/62/M379 reference strain, which has a higher sensitivity to H2 than does MHOM/MX/01/Tab3, was used. The number of parasites/ml was determined at 72 hours of incubation using 100 mM of each compound in four replicates. The culture conditions were the same as described in FIG. 1.

FIG. 4: An example of biological activity of H2 parenterally administered at a dose of 0.1 mg/mL in 100 μl of physiological saline solution; a) and c) correspond to the activity prior to treatment, b) is a control using only a saline solution, and d) is the condition with H2. Images b) and d) were collected at 14 days after treatment.

FIG. 5: An example of the biological activity of the HA2 prodrug dissolved in drinking water and orally administrated at a dose of 1 mg/mL ad libitum for 3 days; a) before treatment, b) three months after treatment, c) six months after treatment, and d) seven months after treatment.

DESCRIPTION OF THE INVENTION Description of the Compound

The compound N⁶-(ferrocenmethyl)quinazoline-2,4,6-triamine (H2) is a solid substance at room temperature and atmospheric pressure. Its contains carbon, hydrogen, nitrogen and iron (II) and has a molecular weight of 374 a.m.u., a condensed molecular formula C₁₉H₁₉N₅Fe, and the following chemical structure:

H2 presents the following physicochemical properties:

Melting point: 210.6-211° C.

R_(f): 0.53 (2-butanol/acetic acid/water 80:20:5)

Infrared spectrum (KBr): 3369 and 3244 (N—H), 1693 and 1668 (C═O), 823 (C—H ferrocene).

Proton nuclear magnetic resonance spectrum (DMSO-d₆): 3.98 ppm (t, J=6, 2H, CH₂), 4.10 ppm (t, J=3, 2H, ferrocene), 4.20 ppm (s, 5H, ferrocene), 4.32 ppm (t, J=3, 2H, ferrocene), 5.3 ppm (t, J=6, 2H, CH₂), 5.51 ppm (s, 2H, NH₂), 6.96 ppm (d, J=2.4, 1H, quinazoline), 7.02 ppm (s, 1H, NH₂), 7.04 ppm (br., s, 1H, quinazoline), 7.049 ppm (br, s, 1H, quinazoline).

Elemental analysis for C₁₉H₂₀FeN₅: Calculated: C, 61.14; H, 5.13; N, 18.76. Measured: C, 61.14; H, 4.92; N, 18.03.

H2 synthesis is initiated by the condensation of N,N′-(6-aminoquinazoline-2,4-diyl)diacetamide with ferrocencarboxaldehyde in dimethylformamide (DMF). Subsequent reduction with sodium borohydride (NaBH₄) gives HA2, which produces H2 in a 62% yield when hydrolyzed in a methanolic sodium hydroxide solution.

It is also possible to prepare H2 prodrugs, i.e., compounds with the same base structure that form H2 when metabolized in a living organism.

TABLE H2 Prodrugs

No. R₁ R₂ R₃ HA2 NHC(O)CH₃ NHC(O)CH₃ H 2 NHCOCH₂CH₂COOH NH₂ H 3 NH₂ NHCOCH₂CH₂COOH H 4 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH H 5 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ H 6 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ H 7 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ H

These compounds can be obtained using the following process:

The synthesis of prodrugs 2 and 3 is initiated by reacting one equivalent of succinic anhydride with H2 in DMF. After stirring at room temperature until the reactants are consumed, the resulting suspension is separated by filtration. The mixture of the obtained compounds (2 and 3) is separated by open column chromatography using silica gel as the stationary phase and chloroform as the mobile phase. The synthesis of prodrugs 4 and 7 is initiated by reacting two equivalents of succinic anhydride with H2 in DMF. After stirring at room temperature until the reactants are consumed, the suspended solution is separated by filtration to obtain prodrug 4, which is reacted with dicyclohexylcarbodiimide and hydroxyurea in DMF at room temperature for 72 hours. The reaction mixture is separated by open column chromatography using silica gel as the stationary phase and a chloroform/methanol gradient as the mobile phase to obtain prodrug 7.

Pharmaceutical Composition:

As part of the invention, the pharmaceutical compositions of H2, derivatives and prodrugs are also presented along with the pharmaceutically acceptable excipients. The following excipients can be employed for the compound synthesis: low-molecular-weight carboxymethylcellulose, high-molecular-weight carboxymethylcellulose, ethanol, Tween 20, Tween 80, Cremophor, polyethylene glycol, propylene glycol, glycerol, triethanolamine, lactose, alpha-cyclodextrin, beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin, heptakis, methyl-beta-cyclodextrin, and gamma-cyclodextrin.

Administration Routes:

The administration of H2, derivatives or prodrugs to biological organisms is performed by any pharmaceutical route that is used and accepted for that purpose.

Biological Activity:

At greater than 5 μg/ml, H2 is lethal to Leishmania in less than 5 hours. The in vitro effect is apparent at 30 minutes after application. The parasite structure is modified such that it loses its characteristic form, loses refringence, becomes spherical, and is incapable of multiplying. H2 has a CL₅₀ of 2.6 μm/ml for the Leishmania mexicana MHOM/MX/01/Tab3 strain. The mechanism of cellular damage could not be identified by means of annexin for concentrations greater than 10 μg/ml; it is thought that a necrosis process rather than apoptosis is likely involved.

In comparison to other compounds with leishmanicidal activity, such as meglumine antimoniate, metronidazole, or hydroxyurea, H2 kills the total amount of parasites more quickly at up to 10-fold faster than any previously described compounds at doses that are ten-fold lower or less. H2 also presents activity against other protozoa, including Trypanosoma, Plasmodium, Entamoeba, and Giardia, as well as metazoan parasites and microorganisms in general.

Cytotoxicity against murine cells was not found in in vitro studies or in vivo studies using oral, parenteral, or dermal administration in mice. The compound was designed to specifically inhibit the activity of vital protozoan enzymes without activity in the human versions.

EXAMPLES 1) Synthesis

Using a 50 ml Florence flask equipped with magnetic stirring, a Vigreux column, and a nitrogen atmosphere, 0.31 g of ferrocencarboxaldehyde (0.00143), 0.3 g of N,N′-(6-aminoquinazoline-2,4-diyl)diacetamide (1 eq.), 1 ml of DMF, and a drop of acetic acid were combined. The mixture was stirred at 85° C. for 45 minutes. The mixture was cooled to 0° C. using an ice-water bath, and 0.0671 g (2 eq.) of NaBH₄ was slowly added. The ice bath was removed, and stirring was continued for 12 hours at room temperature. The DMF was evaporated in a rotatory evaporator, and a saturated solution of Na₂CO₃ was added to the residue. The yellow precipitate that formed was separated by filtration and rinsed several times with water. After drying at room temperature, the solid was rinsed several times with diisopropyl ether to obtain 0.3239 g of HA2 with a 48% yield, R_(f)=0.76 (CHCl₃/MeOH 80:20) and p.f.=218-220° C. HA2 was hydrolyzed with one equivalent of a methanolic sodium hydroxide solution to obtain a precipitate that was separated by filtration. The solid was cleaned in methanol with activated carbon. From this procedure, 0.32 g of a yellow compound (H2) was obtained at a 62% yield, R_(f)=0.53 (2-butanol/acetic acid/water 80:20:5) and p.f.=210.6-211° C.

2) Biological Activity

H2 (3 μg/ml) eliminates more than 90% of the parasites in Leishmania mexicana cultures (Tab3 or M379 strain) with 10⁶ parasites/ml in Dulbecco's medium modified with 4.5 mg/mL glucose and 10% fetal bovine serum.

3) Pharmaceutical Preparation

To prepare a suspension of H2, 10 mg of the substance was dissolved in 1 ml of DMF. Subsequently, 100 μl of the solution was diluted with water (1:10) to obtain a suspension for oral administration to rodents.

4) H2 Derivatives

No. R₁ R₂ R₃  8 NHC(O)CH₃ NHC(O)CH₃ CH₃  9 NHCOCH₂CH₂COOH NH₂ CH₃ 10 NH₂ NHCOCH₂CH₂COOH CH₃ 11 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH CH₃ 12 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ CH₃ 13 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃ 14 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃ 15 NHC(O)CH₃ NHC(O)CH₃ CH₃CH₂ 16 NHCOCH₂CH₂COOH NH₂ CH₃CH₂ 17 NH₂ NHCOCH₂CH₂COOH CH₃CH₂ 18 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH CH₃CH₂ 19 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ CH₃CH₂ 20 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃CH₂ 21 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃CH₂ HO2 NH₂ OH H HO4 OH NH₂ H HO24 OH OH H

5) Prodrug Synthesis

In a 50 ml Florence flask equipped with magnetic stiffing, a Vigreux column, and a nitrogen atmosphere, 0.31 g of ferrocencarboxaldehyde (0.00143), 0.3 g of N,N′-(6-aminoquinazoline-2,4-diyl)diacetamide (1 eq.), 1 ml of DMF, and a drop of acetic acid were combined. The mixture was stirred at 85° C. for 45 minutes. The mixture was cooled to 0° C. in an ice-water bath, and 0.0671 g (2 eq.) of NaBH₄ was slowly added. The ice bath was removed, and stirring was continued for 12 hours at room temperature. Subsequently, the DMF was evaporated in a rotary evaporator. A saturated solution of Na₂CO₃ was added to the residue. The yellow precipitate that formed was separated by filtration and rinsed several times with water. After drying at room temperature, the solid was rinsed several times with diisopropyl ether to obtain 0.3239 g of HA2 at 48% yield, R_(f)=0.76 (CHCl₃/MeOH 80:20) and p.f.=218-220° C.

6) Biological Activity of the HA2 Prodrug and the Derivatives HO2 and HO4

The following is a list of Leishmania mexicana growth inhibition activity by the prodrugs compared to H2 and a control.

Compound % of Leishmania Growth Inhibition Control 0 HO2 20 HO4 25 FBC 32 HA2 24 H2 100 FBC: N-(ferrocenmethyl)aniline 

1-9. (canceled)
 10. A compound selected from the group consisting of H2, HA2, 2-21, HO2, HO4, and HO24, wherein the compound has the structure of Formula (I), and wherein R₁, R₂, and R₃ are as set forth in the table below: Formula (1)

No. R₁ R₂ R₃ H2 NH₂ NH₂ H HA2  NHC(O)CH₃ NHC(O)CH₃ H  2 NHCOCH₂CH₂COOH NH₂ H  3 NH₂ NHCOCH₂CH₂COOH H  4 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH H  5 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ H  6 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ H  7 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ H  8 NHC(O)CH₃ NHC(O)CH₃ CH₃  9 NHCOCH₂CH₂COOH NH₂ CH₃ 10 NH₂ NHCOCH₂CH₂COOH CH₃ 11 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH CH₃ 12 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ CH₃ 13 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃ 14 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃ 15 NHC(O)CH₃ NHC(O)CH₃ CH₃CH₂ 16 NHCOCH₂CH₂COOH NH₂ CH₃CH₂ 17 NH₂ NHCOCH₂CH₂COOH CH₃CH₂ 18 NHCOCH₂CH₂COOH NHCOCH₂CH₂COOH CH₃CH₂ 19 NHCOCH₂CH₂COONHC(NH)NH₂ NH₂ CH₃CH₂ 20 NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃CH₂ 21 NHCOCH₂CH₂COONHC(NH)NH₂ NHCOCH₂CH₂COONHC(NH)NH₂ CH₃CH₂ HO2 NH₂ OH H HO4 OH NH₂ H HO24 OH OH H


11. The compound of claim 10, wherein the compound is N⁶-(ferrocenmethyl)quinazoline-2,4,6-triamine (H2) with the following chemical structure:


12. A pharmaceutical composition comprising a compound of claim 10, in combination with a pharmaceutically accepted excipient or adjuvant.
 13. The pharmaceutical composition of claim 12, wherein the compound of claim 10 is H2.
 14. The pharmaceutical composition of claim 12, wherein the composition is formulated in tablet, capsule, injectable drug, patch, suspension, gel, or granulated form.
 15. The pharmaceutical composition of claim 12, wherein the compound of claim 10 is selected from the group consisting of HA2, 2-21, HO2, HO4, and HO24.
 16. A process for the preparation of a compound of claim 1, the process comprising the steps of: i) condensing N,N′-(6-aminoquinazoline-2,4-diyl)diacetamide with ferrocencarboxaldehyde in dimethyl formamide (DMF) to obtain a condensation product; and ii) reducing the condensation product to obtain a reduction product; or i) reacting of 2,4,6-triaminquinazoline with methyl iodide or ethyl iodide to obtain an alkylated compound; and ii) coupling the alkylated compound with ferrocencarboxaldehyde to obtain a ferrocenmethylquinazoline compound.
 17. The process of claim 16, further comprising the step of hydrolyzing the reduction product to obtain a hydrolyzed product.
 18. The process of claim 17, further comprising the step of reacting the hydrolyzed product with succinic anhydride at room temperature.
 19. The process of claim 18, further comprising the step of reacting the product of claim 18 with hydroxyurea using dicyclohexylcarbodiimide.
 20. The process of claim 17, further comprising reacting the hydrolyzed product with sodium hydroxide.
 21. A method of treating a microbial disease comprising identifying a subject in need thereof and administering to the subject a compound of claim 1, wherein the compound of claim 1 is an antibiotic, microbicide, bacteriological, bacteriostatic, antiparasite, antiprotozoal, or antileishmanial.
 22. The method of claim 21, wherein the subject is a human or an animal. 